Embodiments of the invention relate generally to a system and method for fingerprint collection, and more particularly to a contactless multi-fingerprint collection device.
It is well known that the patterns and geometry of fingerprints are different for each individual and are unchanged over time. Thus fingerprints serve as extremely accurate identifiers of an individual since they rely on un-modifiable physical attributes. The classification of fingerprints is usually based on certain characteristics such as arch, loop or whorl, with the most distinctive characteristics being the minutiae, the forks, or endings found in the ridges and the overall shape of the ridge flow.
Traditionally, fingerprints have been obtained by means of ink and paper, where a subject covers a surface of their finger with ink and presses/rolls their finger onto paper or a similar surface to produce a rolled fingerprint. More recently, various electronic fingerprint scanning systems have been developed that obtain images of fingerprints utilizing an optical fingerprint image capture technique. Such electronic fingerprint scanning systems have typically been in the form of contact based fingerprint readers that require a subject's finger to be put in contact with a screen and then physically rolled across the screen to provide an optically acquired full rolled-image fingerprint. However, such contact based fingerprint readers have significant drawbacks associated therewith. For example, in a field environment, dirt, grease or other debris may build up on the window of contact based fingerprint readers, so as to generate poor quality fingerprint images. Additionally, such contact based fingerprint readers provide a means of spreading disease or other contamination from one person to another.
In a most recent generation of electronic fingerprint scanning systems, contactless fingerprint readers have been proposed where fingerprints are captured without the need for physical contact between a subject's finger and a screen. However, existing contactless fingerprint scanning systems are limited regarding the type of fingerprint images they can acquire. For example, one existing type of contactless fingerprint scanning system is capable of acquiring a single flat image of the finger by utilizing a structured light source. Such single flat images, however, do not provide the entire fingerprint data, as the use of structured light does not allow for capture of a large area of the fingerprint (i.e., the overlap between a camera field of view and that of the structured light is small). Additionally, the technique employed to create contrast between fingerprint ridges and valleys of the single flat image uses a shallow depth-of-field that prevents all areas of the finger, such as the top and sides of the finger, from being in clear focus in the same image.
Another existing type of contactless fingerprint scanning system acquires full 3D images of the fingers using a method such as structured light. However, as set forth above, the use of structured light does not allow for capture of a large area of the fingerprint based on a small overlap between a camera field of view and that of the structured light. Additionally, such 3D fingerprint readers create extra information about the shape of the finger that is not currently used in databases and, as such, the data is not compatible with the vast sets of fingerprint data already on file today.
Therefore, it would be desirable to design a system and method of acquiring a full contactless fingerprint capture that excludes any contact between the hand and the fingerprint reader and that provides full rolled equivalent fingerprint images. Furthermore, it would be desirable to simultaneously capture multiple fingerprints from a subject and provide usability to the general population to adapt to different finger and hand shapes and diversities in the subject's hand eye coordination.